Load the game, and press 'P' to bring up the password system and use any of these level codes.
2--"MRWIMPEY" | 5--"GUNSHOTS"
3--"CLASSICS" | 6--"DOODGUYZ"
4--"WHIZZKID" | 7--"D.GIBSON"
When you are about to be killed for the 4th time, press the LEFT MOUSE BUTTON to bring up the second player, and keep pressing the fire button until you're killed. You will appear at the bottom of the screen.